Joan Rivers participates during the annual Sydney Gay and Lesbian Mardi Gras Parade on Oxford Street on March 7, 2009 in Sydney, Australia. The annual parade, which has been going since June 1978, has a 2009 theme of "Nations United", with the event's intention to raise the visibility of the gay, lesbian, bisexual, transgender, intersex and queer communities.

Joan Rivers' Clinic, Yorkville Endoscopy, Under Investigation

By Tom Winter

The Manhattan clinic where Joan Rivers stopped breathing while undergoing an outpatient procedure on her vocal cords on Aug. 28 is under investigation by the New York State Department of Health, NBC News has learned.

Rivers was at Yorkville Endoscopy when she went into "respiratory or cardiac arrest," according to the New York Fire Department and was transported to Mount Sinai hospital. A spokesman for the Health Department told NBC News that officials are "Investigating the matter."

Physicians at New York Gastroenterology opened Yorkville Endoscopy in 2013.

The 81-year-old comedy legend died on Thursday afternoon at Mount Sinai in New York City, according to her daughter Melissa Rivers.

"My mother’s greatest joy in life was to make people laugh," Melissa Rivers said in a statement. "Although that is difficult to do right now, I know her final wish would be that we return to laughing soon."

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Tom Winter

Tom Winter is a producer and reporter for the NBC News Investigative Unit based in New York. He covers crime, courts, terrorism, and financial fraud on the East Coast.

Previously he has covered high-profile criminal trials, including those of George Zimmerman, Jerry Sandusky trial and Martha Stewart. In addition, he has covered major breaking news events such as the shootings at Virginia Tech and Elementary in Newtown, Conn., and the bombing of the Boston Marathon. While in the New York Bureau, he also covered several hurricanes and natural disaster events.

Winter has over 10 years of experience in radio, television, and online writing and production. He started his career at NBC News as an intern on the TODAY Show and has worked at NBC station WCAU in Philadelphia as well as the National News Desk and the New York Bureau.